Method of manufacturing corrugated paperboard product using a foamed adhesive

Abstract

A vinyl acetate ethylene copolymer adhesive obtains the production of a corrugated paperboard product at ambient temperatures without the need for the heat inputs heretofore required. The adhesive is foamed to expand it so that less adhesive material is required to a given quantity of product.

We claim: 
     
       1. A process for forming a corrugated paperboard product having a corrugated medium fastened to at least one liner, wherein the improvement comprises: providing a water-based emulsion adhesive comprising vinyl acetate ethylene copolymers;   foaming the adhesive so provided;   applying the foamed adhesive at ambient temperature to the flutes of the corrugated medium;   adhering the liner to the medium by means of the adhesive and at ambient temperatures; and   applying pressure to opposite sides of the liner and medium until the adhesive sets.   
     
     
       2. The process of claim 1 further defined as providing an adhesive having from 40 to 55% solids. 
     
     
       3. The process of claim 2 further defined as providing an adhesive having at least 48% solids. 
     
     
       4. The process of claim 1 further defined as providing an adhesive having a viscosity in the unfoamed state of 200-700 centipoises at 25° C. 
     
     
       5. The process of claim 4 further defined as providing an adhesive having a viscosity in the unfoamed state of approximately 300-325 centipoises. 
     
     
       6. The process of claim 1 wherein the adhesive is foamed such that the resulting foamed adhesive has a viscosity in a range of from 1,000 to 4,000 centipoises. 
     
     
       7. The process of claim 6 wherein the adhesive is foamed such that the resulting foamed adhesive has a viscosity of approximately 2,000 centipoises. 
     
     
       8. The process of claim 4 further defined as providing an adhesive including a diluent. 
     
     
       9. The process of claim 8 further defined as providing an adhesive including water as a diluent. 
     
     
       10. The process of claim 1 further defined as providing an adhesive including an insolubilizing agent to enhance the water resistance of the bonds formed by the adhesive. 
     
     
       11. The process of claim 10 wherein said insolubilizing agent comprises oxalaldehyde. 
     
     
       12. The process of claims 1 or 10 further defined as providing an adhesive including a preservative. 
     
     
       13. The process of claim 12 wherein said preservative comprises an aqueous solution of 1, 2 benzisothiazolin-3-one. 
     
     
       14. The process of claim 1 further defined as a method for forming a double faced corrugated paperboard product having a liner on both sides of the medium and wherein the foamed adhesive is applied to the flutes on both sides of the corrugated medium, a liner is adhered to both sides of the medium, and pressure applied to the product without heat. 
     
     
       15. The process of claim 1 further defined as providing an adhesive having 40 to 60% air by weight. 
     
     
       16. The process of claim 15 further defined as providing an adhesive having 50% air by weight. 
     
     
       17. The process of claim 1 further defined as providing an adhesive having a bubble size of 100 microns or less.